NEW YORK, NY, USA - Miami Open champions Ashleigh Barty and CoCo Vandeweghe struck Grand Slam glory at the US Open on Sunday, stunning WTA Doubles No.1 Timea Babos and partner Kristina Mladenovic, 3-6, 7-6(2), 7-6. For both Barty and Vandeweghe, it's a first major title after a combined six runner-up finishes in women's and mixed doubles, respectively.

"I think we have experience with separate partners, but also as singles players also," Vandeweghe said after the match. "We've gone far in a lot of different events separately, but we've had good success this year together when we have played together. I think it's finally the first time we've played together at a Grand Slam. I was just dying for it. She was great to play with for two weeks. I had an amazing time out there with Ash."

Playing their first Grand Slam final as a team, the No.13 seeds didn't drop a set en route to the final and saved three match points to beat the reigning Australian Open champions after two hours and 30 minutes under the Arthur Ashe Stadium roof.

"Obviously we've only played a handful of tournaments together this year, but we've had pretty good success right from the get-go," Barty added. "This last fortnight has been really fun on and off the court. We've been relaxed. We're very hungry to go as deep as we could. It was really nice to be able to play a pretty clean tournament."

Inclement weather didn't hinder Babos and Mladenovic to start, beginning the final on time and eager to increase their 2018 head-to-head against the recently-formed Aussie-American pairing, who beat them in Miami but lost in two subsequent meetings at the Mutua Madrid Open and the Nature Valley Classic in Birmingham.

The two teams exchanged breaks early in the match, but it was Babos and Mladenovic who continued to dictate play, breaking serve again in the sixth game and riding that momentum to take the opning set.

Barty and Vandeweghe upset top seeds Barbora Krejcikova and Katerina Siniakova en route to their first major final as a pair - though Barty has been four times a Grand Slam runner-up with Casey Dellacqua - and put on a courageous display in the second set, trading 12 straight service holds - and saving a pair of championship points in the tenth game - to force a tie-break.

The No.13 seeds nabbed the first mini-break and led 4-2 at the change of ends after a tight forehand from Babos, the reigning BNP Paribas WTA Finals Singapore presented by SC Global champion, who became WTA Doubles No.1 for the first time after Wimbledon and will retain the top spot after the US Open.

Barty and Vandeweghe continued their surge through the sudden death to engineer four set points, only needing one with a fearless backhand return winner from the American to level the match.

Rallying from 0-3 down in the decider, Babos and Mladenovic saved two match points of their own as the Hungarian served down 4-5 in the final set, forcing another tie-break to decide the title.

"We had all the opportunities. We mustn't lie about this," Babos said. "We were all over them and controlling the whole match. I think it just slipped out of our hands in the second set, and then after we were down big-time, and we were really fighting till the end, and this is why they are such a great team. I mean, for now, personally, me, I don't have regrets. We gave everything what we had. It was a great opportunity, but 100% sure that the way we play we will have a lot, lot, lot more."

The No.2 seeds fell behind a mini-break only to win four straight points at the change of ends, earning a third match point at 6-5. Barty and Vandeweghe saved it to earn a third match point of their own on Mladenovic's serve. A double fault from the Frenchwoman - who was a game away from winning the US Open back in 2016 with Caroline Garcia - sealed it for the duo, who engaged in ebullient celebration after the victory.

"I just feel that our game is improving like both of us," Mladenovic said. "This is what I'm really proud of is that we are, like, going deeper in the season and our level is just increasing and we are just improving. We are just enjoying more and more the time together on the court. And then even today when it was tough and we were down in the third set. I believe not many would come back in this situation and give the outcome that was until the very last second.

"I'm personally just very excited for the rest. I know we will have many more and this is not just one this season but many more years."

In all, Barty and Vandeweghe, who came into the US Open under an injury cloud, struck 38 winners to 36 unforced errors - including six aces.

"The whole time we were talking to each other through the whole match," Vandeweghe said. "There were so many ebbs and flows through the match. I told Ash, 'Listen, there's no one I'd rather be out here than with you right now. I believe in you. We're going to get this done.'

"We've been talking about this moment. For me personally, I wouldn't have dreamed this possible at the start of the week of how I entered into the event, not even close to 100%. Even questioning if I was going to play the event. So I definitely didn't think this was going to be a possibility. I'm so happy to be here now at the end with a trophy."